<div>

    <!-- 属性绑定 -->
    <!-- 这样定义动态的classname -->
    <h3 [class.h3-dom]="true">hello</h3>
    <h3 [class]="'h1 h2 h3'">多类名</h3>
    <h3 [class]="['h1', 'h2', 'h3']">数组类名</h3>


    <h3 [style.color]="'red'">style样式</h3>
    <!-- 不常见写法 -->
    <h3 [style.width.px]="300">style样式2</h3>
</div>
